A rigid, slide-open packet of cigarettes comprises a first container, which houses an inner package (defined by a group of cigarettes wrapped in a sheet of foil inner wrapping material) and is housed inside a second container to slide, with respect to the second container, between a closed position, in which the first container is inserted inside the second container, and an open position, in which the first container is extracted partly from the second container. The first container may slide straight with respect to the second container or swing about a hinge connecting the two containers. Some embodiments of rigid, straight-slide-open packets of cigarettes are described in FR2499947A1, U.S. Pat. No. 4,534,463A1, U.S. Pat. No. 5,080,227A1 and IT1169163B, and one embodiment of a rigid, swing-open packet of cigarettes is described in WO2006021581.
The sheet of foil inner wrapping material has a tear-off top portion bounded by a so-called pull-off line, and which is torn off for access to the cigarettes when the packet is unsealed. In the case of a rigid, slide-open packet of cigarettes, only part of the top wall of the inner package is accessible to the user (unlike a conventional rigid, hinged-lid packet of cigarettes), so the tear-off top portion also only involves a limited portion of the top wall of the inner package.
The sheet of foil inner wrapping material is always in the form of an elongated rectangle, and is first folded into a U about the group of cigarettes. Depending on the design of the packing machine on which the packet of cigarettes is produced, the sheet of inner wrapping material may first be folded into a U crosswise or longitudinally about the group of cigarettes. When the sheet of inner wrapping material of a rigid, slide-open packet of cigarettes is first folded into a U crosswise about the group of cigarettes, the tear-off top portion is defined by one part of the sheet of inner wrapping material bounded by one pull-off line.
Conversely, when the sheet of inner wrapping material of a rigid, slide-open packet of cigarettes is first folded into a U longitudinally about the group of cigarettes, the tear-off top portion is defined by two separate parts of the sheet of inner wrapping material, located at opposite ends of the sheet and bounded by two corresponding pull-off lines, as described, for example, in U.S. Pat. No. 5,080,227A1. A tear-off top portion comprising two separate parts of the sheet of inner wrapping material is unpractical, by forcing the user, when unsealing the packet, to tear off the top portion in two consecutive operations (one for each part of the tear-off top portion) as opposed to one single operation.
Moreover, parts of the tear-off top portion of a rigid, slide-open packet of cigarettes may lift off the rest of the inner package and jam against the inner surface of the outer container, thus making it difficult (if not impossible without tearing the packing material) to unseal the packet. (This problem only applies when unsealing the packet, in that, once the packet is unsealed, the tear-off top portion is removed).